Fe2IIIS3-II + 4 HICl 2 H20 + 2 FeIICl2 + 3 S0

This is an oxidation-reduction (redox) reaction:

3 S-II - 6 e- 3 S0 (oxidation)

4 HI + 4 e- 4 H0 (reduction)

2 FeIII + 2 e- 2 FeII (reduction)

Fe2S3 is a reducing agent, HCl is an oxidizing agent, Fe2S3 is an oxidizing agent.